X-ray tube.



PATENTED SEPT. 27, 1904.

0. H. F. MULLER.

X-RAY TUBE.

APPLICATION FILED MAR.15. 1901 N0 MODEL.

v In wektor. Cuifim-oz Wl ti'zessifs I ByZZZZfflZT-ZZ UNITED STATES Patented September 27, 1904.

PATENT OFF C X-RAY TUBE.

SPECIFICATION forming part of Letters ,Batent No. 771,086, dated September 27, 1904.

Application filed March 15, 1901.

To all whom it may concern:

Be it known that I, CARL HEINRICH FLOR- ENZ MULLER, a subject of the German Emperor, and a resident of Hamburg, in the German Empire, have invented certain new and useful Improvements in X-Ray Tubes, of which the following is a specification.

It is well known that the penetrative capacity of the rays emitted by a Rontgen tube is so much the greater according to the rarefaction in the tube is greaterthat is to say, the higher the discharge potential of the same is. These tubes are differentiated into soft and hard highly-rarefied tubes according to the degree of rarefaction. If a tube is highly rarefiedthat is to say, hard-and the penetrative capacity of the rays therefore very great, the tube is less adapted for the irradiation of the parts of bodies of men and animals, for example, because the shadows offer too little contrast, owing to the passage of the rays through the bones. In consequence ofthis in the manufacture of Rontgen tubes intended for irradiation purposes rarefaction is only carried to such a point that the tubes remain soft, so that the penetrative power of their rays may not be too great. v In use, however, the degree of rarefaction increases and the tube soon becomes hard. Various means have been adopted in order to obviate this gradual and undesirable increase in the degree of rarefaction. These means include the warming of the tubes, especially the anode and cathode tube, by means of a spirit-flame, also by surrounding the cathode end with a wet bandage and the heating of a small quantityof caustic potash or a similar substance arranged in a small annex of the tube proper. These means present the defects of being both troublesome and inefficient, and in practice it has been shown that it is hardly ever possible to select the exact time and manner of their employment and frequently tubes which were too hard are made too soft.

As a result of numerous experiments I have invented a device which permits of reducing the hardness of Rontgen tubes to the proper degree for irradiating purposes without danger of failure.

Serial No. 51,363. (No model.)

have illustrated one embodiment of my invention and have shown a central vertical section of a Rontgen tube provided with one form of my improved device.

The Rontgen tube 'r, of any desirable shape, is provided in the usual manner with an anode a, a cathode 7), and an anticathode o. In the structure shown I have provided a subsidiary tube a, communicating with the main tube 0' by means of a tubular branch (Z. In this subsidiary tube I arrange a secondary anode f and a secondary cathode of any suitable shape, and upon the free end of said secondary cathode I secure a body capable of giving off a gas or vapor when subjected to the action of heat. In the drawings I have shown the secondary anode and cathode rod-shaped; but this is not essential to my invention. It will be evident that the passing of an electric spark or discharge from the secondary cathode will cause the body above mentioned to evolve a gas, thereby permitting the regulation of the vacuum in the vacuous space of the tube. In practice I prefer to use a mineral non-conducting substance having the property of giving off a gas or of being decomposed by the action of heatas, for instance, a disk of mica h-but other substances may be used which have the property of evolving gas and which are not non-conductors. It will be understood that commercial mica contains a certain amount of occluded gas and is not chemically pure, and it is this commercial mica which is adapted for use as a vacuum-regulating medium.

I may, if desired, arrange the pair of electrodes f and 9- within the Rontgcn tube '2' itself instead of placing them in a subsidiary tube, and the non-conducting substance it may also be placed not directly upon but in close proximity to the cathode g.

The operation of my improved device is as follows: If the Rontgen tube 1' exhibits too great a degree of hardnessthat is to say, if the penetration ofthe X-rays is too greatthe electrodes f and g of the subsidiary tube 0 are inserted in an electric circuit, (which may advantageously be in shunt upon the inductor of the Rontgen tube,) and the electrodes of the latter may be connected to or disconnected. from the inductor. Owing to the passage of the current between the subsidiary electrodesf and 9, minute particles of the substance of which the non-conducting body It is composed are released and decomposed and yield a medium Which reduces the too great degree of rarefaction in the Rontgen tube. I find that by mounting the gas-evolving substance directly upon the end of the secondary cathode and in the path of the secondary discharge it is by far more efficient and speedy in its action, as it is not only affected by the heat of bombardment, but being in physical contact With the cathode is affected by the heat thereof by conduction as Well. By forming this substance into the shape of a disk and securing it on the end of the cathode it is directly in the path of the discharge and at the same time offers a maximum surface to be effected thereby.

Practical experiments with this device have demonstrated that the proper degree of rarefaction may be arrived at With the greatest certainty Without its being necessary to carefully regulate the period during Which the current passes through the subsidiary electrodes f and g, the strength of current or the distance betweer the said electrodes. An indication of the production of the desired result is the reappearance of the bluish light in the Rontgen tube, Which light is caused to disappear With increasing rarefaction by the increased strength of the fluorescent light which is produced in the glass walls of the tube by the X-rays. By the reappearance of this bluish light and the hue of the same any one at all skilled in the use of such apparatus is able to tell When the degree of rarefaction has been reduced to the proper extent. This appearance is either not produced at all or only very incompletely by the known methods for regulating the degree of rarei'action above referred to.

It is obvious that many modifications and changes may be made in my invention Without departing from the spirit thereof, andl do not limit myself to the particular form shown and described; but

What I claim, and desire to secure by Letters Patent, is-

1. A vacuum-tube having primary anode and cathode terminals located therein, a secondary cathode-terminal located in the same vacuous space and a disk composed of a gasevolving substancemounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

2. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating with the main tube, a secondary cathode located in said subsidiary chamber, and a disk composed of a gascvolving substance, mounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

8. A vacuum-tube having primary anode and cathode terminals located therein, a secondary cathode-terminal located in the same vacuous space and a mica disk mounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

4. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube, a secondary cathode located in said subsidiary chamber, and a mica disk mounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

5.- A vacuum-tube having primary anode and cathode terminals located therein, a secondary cathode-terminal located in the same vacuous space and a disk composed of a nonconducting and gas evolving substance mounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

6. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube, a secondary cathode located in said subsidiary chamber, and a disk composed of a non-conducting and gas-evolving substance, mounted upon said secondary cathode and responsive to a thermal change therein, substantially as described.

7. A vacuum-tube having primary anode and cathode terminals located therein, a set of secondary terminals in the same vacuous space as the primary terminals and a gas-evolving substance mounted upon the secondary cathode responsive to a thermal change therein, substantially as described.

8. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube, a set of secondary terminals in said subsidiary chamber, and a gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

9. A vacuum-tube having primary anode and cathode terminals located therein, a set of secondary terminals in the same vacuous space as the primary terminals and a non-conducting and gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

lO. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube, a set of secondary terminals in said subsidiary chamber, and a non-conducting and gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

11. A vacuum-tube having primary anode and cathode terminals located therein, a set of IIO secondary terminals located in the same vacuous space as the main terminals and a disk composed of a gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

12. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating with the main tube, a set of secondary terminals located in said subsidiary chamber and a disk composed of a gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

13. A vacuum-tube having primary anode and cathode terminals located therein, a set of secondary terminals located in the same vacuous space as the main terminals and a disk composed of a non-conducting and gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

. 14:. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube, secondary terminals located in said subsidiary chamber and a disk composed of a nonconducting and gas-evolving substance mounted upon the secondary cathode and responsive to a thermal change therein, substantially as described.

15. A vacuum-tube having primary anode and cathode terminals located therein, a secondary cathode-terminal located in the same vacuous space as the main terminals and a mica disk secured to the secondary cathode for regulating the vacuum of the tube, substantially as described.

16. A vacuum-tube having primary anode and cathode terminals located therein, a subsidiary chamber communicating With the main tube a secondary cathode located in said subsidiary chamber and a mica disk mounted upon said secondary cathode for regulating the main tube, substantially as described.

17. A vacuum-regulator comprising a set of electrodes and a disk of a gas-evolving substance mounted upon one of said electrodes and responsive to a thermal change therein; substantially as described.

18. A vacuum-regulator comprising aset of electrodes and a disk of mica mounted upon one of said electrodes and responsive to a thermal change therein; substantially as described.

CARL HEINRICH FLORENZ MULLER.

Witnesses:

MAX KAEMPFF, E. H. L. MUMMENHOFF. 

